Ion-Implantation-Induced Damage Characteristics Within AlN and Si for GaN-on-Si Epitaxy

A systematic study was conducted to further understand the physical origin of stress modification in AlN overgrown on Si(111) upon ion implantation and annealing. Implantation parameters including ion size, energy, dosage, and current density were varied, and their effects on the amorphization process in Si(111) substrates were examined. The creation of a thick (>120 nm) amorphous Si (a-Si) layer was previously shown to result in isolation of an epitaxial AlN film grown on a Si(111) substrate through implantation-induced amorphization of the substrate, and this mechanical isolation resulted in stress dilution in the AlN layer. Results show that implanting at current density of 2 mA/cm2 allows for only a thin amorphous layer to be created because of the effects of dynamic annealing, which simultaneously eliminates any damage created from the ion implantation, regardless of ion species, dosage, and energy. Lowering the current density to 0.2 mA/cm2 does create a thick a-Si layer; however, the amorphization disappears during a high-temperature (HT) anneal. Lowering the current further to 0.2 μA/cm2 creates a thick a-Si layer that can be maintained through a HT anneal, with this difference arising from the interfacial quality of the a-Si and crystalline Si (c-Si) boundary.